Process of making acetylene from higher saturated hydrocarbons



PROCESS OF MAKIiIG ACETYLENE FROM HIGHER SATURATED HYDROCARBONS Filed May 26, 1931 J. Taulz Patented ruocuss OF G ACE more mom sn'roas'run 'nocannous Paul Kai-15mm, Germany, Carlo Rossettr, Yverdon, Switzerland, and Jenii Tausz,

Karlsruhe, Germany,

assignors Y to the firm Society ot- Chemical Industry in Basle Basel,

. Switzerland Application May 26,1931, Serial No. -i0,l8li

In Germany June 6, 1930 2 s. (or. cor-4n) the blower" G in thedirection indicated by the Thepresent invention relates to a process of making acetylene from higher saturated hydrocarbons by means of the electric arc.

It is known that acetylene can be made by 5 passing a higher saturated gaseous, vaporized or atomized hydrocarbon through an electric are.

We have made the surprising discovery that a very considerable proportion of the energy of the electric arc can be utilized for the production of 1c tionof the acetylene in the gases which leave the are raised to a very substantial value by increasing the energy density of an extremely short electric arc of low tension with respect to at least one of the electrodes to a'value in the neighbourhood of that at which a loss of substance of the electrode exceeding the normal wear and tear commences.

By the term higher saturated hydrocarbons 7 We understand: hydrocarbons'of the paramn or olefin series, such as methane, ethane, ethylene and homologues thereof, in pure form or as mixtures with other gases, as for instance earth gas, cracking gases, coke oven gas, coal gas or other as gases resulting from distillation of carbonaceous material, or constituents of cracking gases, coke oven gases, coal gas, or of other gases resulting from the distillation oi carbonaceous material, further hydrocarbons resulting from the working up of petroleum, such as benzine, gas oil, fuel oil and the like, further aromatic hydrocarbons, such as benzene, toluene, naphthalene and the like. Of course also mixtures of the above mentioned hydrocarbons may be employed. Further one may also employ h drocarbons which already contain a certain amount of acetylenaior instance the gases which remain after separating the bulk of the acetylene from the mixture resulting from the process described'below. The presence of foreign gases, as for instance hydrogen, nitrogen, precious gases is not detrimental so long as they do not attain too high a concentration. If nitrogen be present, a certain amount of hydrocyanic acid isformed besides acetylene, whichformer may easily be eliminated by absorption in an alkaline medium.

It has proved advantageous to perform; this process in a cyclic manner such described in Patent No. 1,543,714.

An apparatus suitable for cyclic operation is illustrated diagrammatically in the accompanying drawing.

K is a continuous tubular system constructed,

for example, of ironin which the gases or Vapors acetylene and at the same time the concentra-- .being introduced through the inlet E.

mixture withdrawn from the system had the following crimpositiomto be treated are caused to circulate by means of insulated-fromthe system K and constructed .in

the form of a tube through which a partof the gases circulating in the system is withdrawn irorn the arc. L is a counter-electrode.

The following example .the invention:----

In the apparatus above described there was used as one-electrode a carbon rod. cffid mm. diameter and as the other electrode a carbon tube of internal diameter 14 mm. and wall thickness Ill 10.5 mm. The distance between the electrodes, whichdepends to a certain extent on the velocity with which the gases are circulated, was about 2 mm. A. direct current electric arc was struck between the electrodes, the potential being about to "38 volts and the current strength about 350 amperes. The system K was filled with methane which was caused to circulate with a high velocity by means of the blower G. 1'. cubic metres of gas were withdrawn per hour by way'of the elec-i trade A, a corresponding quantity of fresh gas The gas CZHZ 9.55 C2H4 (1H4 4935 H2 @011 U it will be seen from the above figures that expenditure of energy of 6,8 kilowatt-hours was required for the production of l kilo of acetylene.

"The temperature of-the gases circulating in the cooled. The pressure within the system K exceeded the externail atmospheric pressureby about 0.15 atmosphere,

Per centby volume to when the energy density of the electric arcwas 10 increased above that corresponding the above example, a point was quickly reached at which a. small loss of substance'of the electrode could be detected; the utilization of the energy at this point was equallygood. 'Whem'on the other ice by way of the electrode 'A until they show the acetylene in the withdrawn gases was observed.

For example, when the potential of the arc was about 35 volts and the current about 180 amperes,

15 kilowatt-hours were required for the production of one kilo of acetylene; when the potential of the arc was about 30 volts and the current about amperes, about 23 kilowatt-hours were required. I

In carrying out the invention attention must be paid to the following points. When one of the variable conditions is altered (pressure, temperature, energy density, speed of circulation of the gases, etc.) then a new optimum must be found by suitable variation of the other conditions; this,

however, may be quickly carried out... For ex-' ample, in order to attain the high utilization of energy and satisfactory concentration of'the gases in acetylene in an apparatus having other dimensions one may proceed empirically as follows:

The energy density is first determined at which a loss of substance of the electrode exceeding the normal wear and .tear commences and is maintained in the neighbourhood of this point whilst.

the gas is caused to circulate with a high velocity. Thereupon the inlet E is connected with ,a source of the gas which is to be admitted (gas container) and increasing quantities of gas are withdrawn desired concentration in acetylene. The rate at which gas is withdrawn from the system is then further increased until the desired concentration of acetylene begins to fall substantially. In this manner the optimum conditions are found and may then be maintained, the velocity of the circulating gases in the system K being, if necessary, varied in order to repress, as far as possible, the formation of soot. The conditions given in the example,that is to say energy density (correspondingly the cross-sectional area of the electrodes), and the rate of withdrawal of gas at a concentration of 10 per cent of acetylene in the withdrawn gas, show how it is possible easily and quickly to adjust the variable operating conditions to produce economically favorable results.

In certain circumstances it may be desirable touse electrodes containing additions, the vaporizable portions of which may mix with the stream of gas; in this respect there come particularly into question substances which influence the electrical conductivity in the zone of the electric arc.

When there is used a vaporized or atomized hydrocarbon the circulatory system must be so constructed that there is always a sufiicient quantity of hydrocarbon in circulation, that is to say one must operate in a heated circulatory system. For this purpose the whole system is advantageously heated by means of a steam jacket or otherwise to a temperature at which the hydrocarbon introduced to the system has a suflicient high vapor tension. When a mixture of hydrocarbons is used the temperature need only be such that a sufficiently large fraction of the hydro- I carbons has the required vapor tension. In the latter case, at the boiling point of one fraction of the hydrocarbon mixture the remaining fractions, which are still at a temperature below their boiling points, are atomized to such a degree that the hydrocarbon mixture is to a suflicient extent in the desired fine state of subdivision. It is frequently possible to maintain a sufflciently high temperature by merely insulating the system against loss of heat.

It has proved especially useful to generate the electric arc with direct current, which latter may be of low tension.

The process may be conducted at atmospheric pressure or at a pressure higher or lower than atmospheric pressure; operation under a raised pressure is to be recommended since it involves an improvement in the utilization of the energy.

The invention permits the production of acetylene by means of the electric arc with a surprisinglysmall consumption of energy and simultaneously a remarkably high concentration of acetylene in the gases.

Having regard to the low cost of the parent materials, disturbance of the process owing to the simultaneous formation ofsoot and hydrogen is insignificant; thus, when operating in the manner described in the example there was pro- 'duced at the most 200 grams of soot for each kilo of acetylene.

If there is used as an addition to the electrodes, as hereinbefore referred to, a substance such as lime whose carbide or carbide components are vaporized, it is advantageous to give only one electrode a high carbide content or to use only one carbide electrode, whilst the other is wholly or in greater part a carbon electrode the loss of substance of which may then serve as an indication of the electrical energy density to be used in accordance with the invention.

There may be used more than one tubular electrode, which may serve both for the introduction of gases into the system and for the withdrawal of gases from the system.

What we claim 'is:--

1. In the manufacture of acetylene by treating higher saturated hydrocarbons in the electric arc, the step which consists in maintaining the energy density of an electric arc of 2 millimeters length and of low tension with respect to at least one o the electrodes in the neighbourhood of that at which a loss of substance exceeding the normal wear and tear commences.

2. Process according to claim l, wherein the materials under reaction are made to circulate with great velocity, fresh gases being'simultaneously introduced at one point of the cycle and the reaction gases being removed at another point of the cycle, the speed of the current of the gases streaming into and out of thja cycle being kept lower than' the speed of he reacting gases in the cycle.

CARLO nossn'rrr. 1 

